The Exxon Valdez oil spill recently marked its 20th anniversary, a reminder of the devastating impact that human activity can have on even the farthest reaches of the planet. These images convey the scale and sadness of nine other enviro-disasters, both past and ongoing.

A product of U.S. Army-sanctioned mass slaughter of American bison in the 1800s, these bison skulls are waiting to be ground for fertilizer, most likely in the American midwest. The slaughter was so "effective" that the population of bison in the U.S. is estimated to have dropped from around 60 million in 1800 to as few as 750 in 1890.